Wao i love this question. Because many customers and friends ask this question. It's like the most basic symptom and question.
Here are a few reasons (but not limited to if you want to be an asshole) on why your leaf turned yellow:
1. Your plant is asking for your attention.
2. Your plant is screaming for help.
3. Nutrient deficiency. Nutrient toxicity.
1. Help. Something's not right. You did something wrong. Omg what is it.
Doctor is here doctor will tell you.
Check the leaf.
Does it feel soggy especially the bottom leaves?
You have over watered.
Does it feel crispy?
You have under watered. Actually most of the time it becomes brown instead of yellow if it dries up.
Can you identify which part became yellow? The entire leaf? Marginally? You dk?
Did you accidentally pour the entire bottle of fertilizer inside?
Did you recently transplant your plant?
Is your soil is literally flooding? dry like desert?
High soil pH.
Sometimes, it's a combination of all the reasons above! There's actually too many if you really want to think deeply about it. I'll generally explain more in the video.
In other countries there may be other reasons like winter frost.
Urm ok no actually the plant looks pale. It's not the right shade of green.
Oh, maybe somebody washed your leaves then lak sek ha.
Your plant is experiencing the chlorosis effect where there is loss of the normal green coloration of leaves of plants. This can be caused by lack of light, disease, or some specific reasons like iron deficiency. Why will the color become less green? This happens when chlorophyll is insufficiently produced.
Yes it is a universal sign that your baby is under stress and it's time to relook into its health.
2. You have left the mistake hanging on for too long. Ok shit now all my leaVES turned yellow. Does the plant look overall-y sick?
When it comes to this point chances are your plant had received a significant amount of damage and it may or may not affect the survivability of the plant, depending on how strong your plant it. It's like when you're sick, or you have high blood pressure and the doctor tells you you have to live on medication forever because you have a permanently damaged system. Either you die from it, die with it, or more attentive maintenance has to be done consistently, until, hopefully it recovers completely or grow new parts.
Gg for you babe. Just kidding, topic 11 i will speak on how we can "resurrect" your plant. 起死回身.
Wu ya boh Pearlina... hahahahaha.
3. Facts that school taught me:
Nitrogen (N) deficiency causes light green to yellow appearance of leaves especially in older leaves.
Magnesium (Mg) deficiency causes initial yellowing of older leaves between leaf veins spreading to younger leaves. Yellowing of older leaves starts from the edges inwards. Sulpher (S) deficiency causes initial yellowing (chlorosis - i thought you what is it just now) of young leaves spreading to whole plant; similar symptoms to nitrogen deficiency but occurs on new growth (young shoots). Iron (Fe) deficiency causes initial distinct yellow or white areas between veins of young leaves leading to spots of dead leaf tissue. Zinc (Zn) deficiency is not yellowing, but may seem yellowing again due to chlorosis. It will reflect on the upper, new leaves and can be either interveinal chlorosis, or a band of chlorotic tissue between the leaf edge and the midrib. The symptoms begin at the leaf base and expand toward the leaf tip.
Manganese (Mn) deficiency causes interveinal yellowing or mottling of young leaves.
Okay already TMI for beginners. But yeah.